Credentials include identification cards, driver's licenses, passports, and other documents. Such credentials are formed from credential or card substrates including paper substrates, plastic substrates, cards and other materials. Such credentials generally include printed information, such as a photo, account numbers, identification numbers, and other personal information. Credentials can also include data that is encoded in a smartcard chip, a magnetic stripe, or a barcode, for example.
Credential production devices process credential substrates by performing at least one processing step in forming a final credential product. One such process is a transfer or laminating process that transfers a material to a surface of the card substrate using a heated roller. This process can be used to transfer an image to the surface of the card substrate and/or provide protection to the surface of the card substrate from abrasion and environmental conditions, for example.
The material transferred to the surface of the card substrate using the heated roller is generally one of two types: a patch laminate, or a fracturable laminate or transfer layer often referred to as a “thin film laminate.” The patch laminate is generally a pre-cut polyester film that has been coated with a thermal adhesive on one side. The pre-cut patch is removably attached to a continuous carrier layer which is generally a coated polyester material. The pre-cut patch is attached to the liner with the thermal adhesive side exposed and available for lamination to the substrate. The heated roller is used to heat the patch to activate the adhesive and press the patch to the surface of the substrate to bond the patch onto the surface.
One disadvantage to the use of a patch laminate is that it does not provide edge-to-edge protection to the surface of the card substrate because it must be formed slightly smaller than the surface of the card to ensure that the patch laminate does not extend beyond the card's edges. Another disadvantage to the use of the patch laminate appears when the surface of the card substrate requiring protection includes a feature over which the patch laminate should not be applied. Such features may include, for example, a magnetic stripe, a signature panel, a surface hologram feature, or electrical contacts of a smartcard module. In order to provide protection of graphics when these features are present, portions of the patch laminate must be removed prior to lamination to expose the feature. Further, it may be desirable to avoid heating some portions of the surface of the card substrate, something which is generally not possible using the heated roller.
Transfer layers are generally continuous resinous materials that have been coated onto a continuous carrier layer or backing to form a transfer ribbon. The side of the resin material that is not attached to the continuous carrier layer is generally coated with a thermal adhesive which is used to create a bond between the resin and the surface of the substrate. The heated roller is used to activate the adhesive and press the resinous material against the surface of the substrate to bond the material to the surface. The carrier layer or backing is removed to complete the lamination process.
The transfer layer may also be in the form of a print intermediate, on which an image may be printed in a reverse-image printing process. In the reverse-image printing process, an image is printed to the exposed side of the transfer layer. Next, the image on the transfer layer is registered with the card substrate. The heated roller is used to activate the adhesive on the imaged transfer layer causing the imaged transfer layer to bond to the surface of the card substrate. A backing of the overlaminate material is removed from the bonded imaged transfer layer to complete the transfer of the image to the card substrate.
The transfer layer provides a degree of protection to the surface of the substrate as well as the image printed on the transfer layer. Some transfer films include a protective layer that is configured to provide an additional level of protection to the surface and image. In general, the protective layer increases abrasion resistance, but can also provide protection from other environmental conditions, such as moisture, ultraviolet light, etc.
In most applications, the transfer ribbon is positioned to completely cover the surface of the substrate. Ideally, as the carrier layer is pulled from the portion of the transfer layer bonded to the surface of the substrate, the transfer layer fractures along the edges of the substrate. This results in the entire surface being covered by the transfer layer for full edge-to-edge protection of the surface. Unfortunately, the transfer layer does not always cleanly transfer to the substrate.
Edge flash occurs when the transfer film does not fracture properly along an edge of the substrate, such as the trailing edge, during the carrier peeling phase of the transfer lamination or reverse-image printing process. This results in portions of the transfer film remaining adhered to the carrier layer or the substrate that were respectively intended to bond to the substrate or the carrier layer, and defects in the processed substrate. Edge flash tends to be more problematic as the thickness of the transfer layer increases, such as due to a thick protective layer. As a result, the thickness of the transfer layer used in conventional transfer lamination processes and devices is limited to avoid edge flash issues. Unfortunately, this also limits the level of protection that may be provided to the surface of the substrate by the transfer layer.
Sometimes full edge-to-edge coverage of the surface of the substrate with the transfer layer is not desired. For instance, it may be necessary to avoid covering certain features that may be present on the surface of the substrate, such as, for example, a magnetic stripe, a signature panel, and other features mentioned above. One technique that is used to prevent the transference of the transfer layer to select portions of the card surface involves the use of an inhibitor panel of a print ribbon. The inhibitor panel is positioned over the imaged transfer layer of the transfer ribbon, and the print head selectively activates portions of the inhibitor panel corresponding to portions of the imaged transfer layer that should be prevented from being transferred to the surface of the substrate. The activation of the selective locations of the inhibitor panel cause those activated portions of the inhibitor panel to adhere to the corresponding portions of the imaged transfer layer through the activation of the adhesive in the transfer layer. As the print ribbon is pulled away from the imaged transfer ribbon, the activated portions of the inhibitor layer remove the corresponding imaged transfer layer portions from the transfer ribbon. The transfer ribbon then includes the remaining imaged transfer layer which was not removed through bonding with the inhibitor layer of the print ribbon. The gaps in the imaged transfer layer on the transfer ribbon that correspond to the removed sections of the imaged transfer adhesive correspond to the locations of the features of the substrate where the transference of the transfer layer is undesired. Accordingly, the sections of the substrate where the transference of the imaged transfer layer is undesired remain free of the transfer layer following the transference of the imaged transfer layer from the transfer ribbon to the surface of the substrate using the heated roller.
As with edge flash, the thickness and durability of the transfer layer also affects the success of the above-described transfer layer removal process. For instance, thick transfer layers are subject to tearing during the transfer layer removal process resulting in the undesired removal of non-activated portions of the transfer layer and/or the failure to remove activated portions of the transfer layer. This prevents the substrate from receiving the desired portions of the imaged transfer layer, resulting in defects.